The present invention relates to a small-sized illuminator provided with an LED (light-emitting diode) which is used as a room light or a map light of a vehicle to illuminate the cabin and the interior of a container for small items such as a console box, a glove compartment, an accessory pocket, or an ash tray. It may also illuminate a cup holder or the area of passengers' feet.
FIG. 6 shows a first example of a related-art illuminator which is disclosed in Japanese Patent Publication No. 9-272377 (cf., pages 2–4, FIG. 1).
In this example, an illuminator 60 is capable of illuminating the interior of containers for small items such as a console box 66 with adequate luminance at low power consumption. The illuminator comprises a main body 61, a circuit board 63 attached to the main body 61, and a lens 65 which covers the circuit board 63.
The main body 61 is formed in a box-shaped general configuration using a synthetic resin material. A mount 62 for mounting the illuminator 60 to a surface of a wall of the console box 66 is provided in a lower part of the main body 61. Each of the circuit board 63 and the lens 65 is securely held on the main body 61 using an engagement member.
A plurality of LED chips 64 are mounted on the circuit board 63. The LED chips 64 are arrayed and connected to an alternator and a battery through branch lines 66 so that the emitted light linearly. The circuit board 63 is also provided with electronic components such as a rectifier diode for preventing noises and a current limiting resistor which are not shown.
The lens 65 is formed in a box-shaped configuration from a highly transparent synthetic resin material. Therefore, light emitted from the LED chips 64 is converged as it passes through the lens 65 to illuminate the interior of the console box 66 with high luminance.
With such a configuration, since a large number of LED chips 64 are mounted, an illuminator can be provided which can illuminate the interior of a container for small items with sufficient luminance and which consumes small power.
In this example, since ends of the two branch lines 66 are connected to the circuit board 53, a new branch line 66 must be formed on the trunk line to provide an additional illuminator. This is troublesome and costly, and a problem arises in that an additional illuminator cannot be easily provided.
Further, since the plurality of LED chips 64 is mounted on the circuit board 63, a problem arises in that the main body 61 is therefore large-sized and cannot be mounted to a container for small items which has only a small space therein. For example, the lamp may not be mounted to an ash tray or cup holder. When the intervals between the plurality of LED chips 64 are decreased to reduce the size of the illuminator 60, a problem arises in that the temperature in the illuminator 60 increases because of poor heat radiation to reduce light-emitting efficiency. In particular, a red LED chip may undergo an abrupt reduction of light-emitting efficiency at a high temperature.
When the illuminator 60 is used in a container for small items such as an ash tray or cup holder, it will sufficiently work with a small number of LED chips 64 because high luminance is not required. When the illuminator 60 is used in a console box or a glove compartment or used as a map light, it must have a large number of LED chips 64 because high luminance is required. While the number of the LED chips 64 depends on the size of the container for small items or the place to be illuminated, the illuminator 60 cannot accommodate an increase or decrease in the number of the LED chips 64 with flexibility. It is therefore required to redesign the main body 61, the circuit board 63, and the lens 65 to satisfy such a requirement, which results in the problem of an increase in total cost including tooling costs.
FIG. 7 shows a second example of an related-art illuminator. In this example, illuminators 70 which are mounted in containers for small items such as a console box and glove compartment in a way similar to that in the first example. The illuminators 70 are connected to a wire harness 75 provided in a vehicle through joint connectors 71, branch lines 72, and module-side connectors 73 in a manner so-called bus-type connection.
When an additional illuminator 70 is to be provided, a new joint connector 71, branch line 72, and module-side connector 73 are prepared and are arranged along the wire harness 75 similarly to the other illuminators 70 in parallel with them.
In this example, although it is advantageous in that connecting operations are simple because the illuminators 70 are connected to ends of the branch lines 72 using connectors, there is a problem in that the illuminators cannot be made small. Further, since the illuminators 70 are connected to the wire harness 75 through the joint connectors 71, the branch lines 72, and the module-side connectors 73, there is a problem in that a large number of components are involved to result in a high total cost. Further, since the illuminators 70 are connected to ends of the branch lines, not intermediate portions of the same in a manner similar to that in the first example, there is a problem in that it is uneasy and troublesome to provide an additional illuminator 70.
FIG. 8 shows a third example of an related-art illuminator. The present example is different from the second example in that a plurality of illuminators 80 is serially connected to a branch line 81 which branches from a wire harness.
Each of the illuminators 80 is constituted by a case 87 formed by a base 84 and a cover 86 and a connecting circuit. Both of the base 84 and the cover 86 are provided by molding a synthetic resin material having insulating properties. An intermediate section of the branch line 81 is soldered to the connecting circuit.
In this example, a redundant part 81a of the cable 81 is left between the adjoining illuminators 80 to facilitate the assembly of each of the illuminators 80. However, if the redundant part 81a is too long, the cable can be flapped by vibration of the vehicle when it is running, which results in the problem of the generation of noises and damage of the cable due to interference with its surroundings.